I wish I had a nickel for every mother who send her kid to my preschool class dressed up in their patent leather party shoes and satin dresses or their dress pants and white shirts. Then they complain when the kids come back with even a wild hair peeking out from under the braid.
I let my son be a little piggie all the time. I want him to experiment with new food, which means I have to let him eat his yogurt on his own. He gets filthy. I will wipe him down before we go in public, and maybe change his clothes if they are gross, but if we stay at home, he only gets the occasional wipedown until his bath-time.
When I was a kid I used to intentionally get as dirty playing outside as I could. I used to bury myself in the dirt. I would scrub dirt into my skin, just because I felt it was cool how dirty the bath water got and how refreshing my bubble bath was.
As long as your kids are happy and don't smell, let them wallow. Who cares what the paper doll mommies say.